Power operated device for selectively moving load elements to predetermined positions



Nov. 22, 1960 B. T. RANDALL 2,951,015

POWER OPERATEO DEVICE FOR SELEOTIVELY MOVING LOAD ELEMENTS TO'PREOETERMINED POSITIONS 5 Sheets-Sheet 1 Filed Nov. l2, 1957 INVENTOR.BURTON 'E RANDALL.

BY BUCKHORN9 CHEATHAM BLORE.

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ATTORNEYS Nov. 22, 1960 B. T. RANDALL.

POWER OPERATED DEVICE FOR SELECTIVELY MOVING LOAD ELEMENTS ToPREOETERMINEO POSITIONS Filed Nov. 12, 195'.

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POWER OPERATEO DEVICE FOR SELEOTIVELY MOVING LOAD ELEMENTS ToPREDETERMINED POSITIONS Filed Nov. l2, 195'? 5 Sheets-Sheet 5 u t, y h@Q t a m a S l l :u V I IH i n "2 Se Q Ll.. s: S

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n BURTON T. RANDALL ll" BY BUCKHORN CHEATHAM K BLORE AT TORNEYS PatentedNov. 22, 1560 PGWER GiERATEIB DEVECE FR SELECTIVELY li/lOVlNG LADELEMENTS T PREDETER- MINED PSlTIGNS Burton T. Randall, Roseburg, Greg.,assigner to C. & D. Lumber Co., Riddle, reg., a partnership anni Nov.12, 1957, ser. NQ. 695,728

14 claims. (ci. 143-37) This invention relates to a power operateddevice and more particularly to a device in which a piston actuated byfluid under pressure in a cylinder containing such piston may be stoppedin yany one of a plurality of predetermined positions relative to thecylinder and such stopping of the piston is cushioned in any of suchpositions by controllable release of fluid pressure from a supplementalvariable volume chamber in the cylinder, the invention also relating toa power operated device in which a plurality of pistons and cylindersare connected in series so that a plurality of load elements may each bemoved to any one of a plurality of predetermined positions relative toeach other and to a lxed element, such arrangement employing the stopdevice referred to above and preferably also the cushioning arrangementalso referred to above.

In my copending application Serial No. 583,162, filed May 7, 1956, nowPatent No. 2,821,172, issued January 28, 1958, I have disclosed a poweroperated device in Awhich a piston is moved in either direction relativeto its cylinder to any one of a plurality of predetermined positions andin which the final movement of the piston relative to the cylinder isalways in one direction. Movement in such direction from one of thepredetermined positions to another is accomplished by rst moving thepiston in the opposite direction, releasing the stop device and thenmoving the piston in the lirst direction until the desired predeterminedposition is approached at which time the stop device is engaged to stopthe piston. Movements from one predetermined position to another in theother direction is accomplished by moving the piston away from the stopdevice past the desired predetermined position then reversing thedirection of the travel of the piston and engaging the stop device. Suchdevice does accurately enable a piston driving a load to be accuratelybrought to predetermined positions relative to the cylinder but in caseswhere the load is of relatively large size so as to produce high inertiaforces during the stopping of the piston and load, the stop mechanism issubjected to excessive stresses. In the copending application referredto above, a supplemental piston and cylinder is employed to produce acushioning action to gradually stop the piston and load moved thereby.

In accordance with the present invention, it has been found that aneffective cushioning action can be produced in the same cylinder byemploying a second piston providing a variable volume chamber betweenthe two pistons in the cylinder in addition to the variable volumechambers at the ends of the cylinder. The stop device referred to abovestops the iirst piston with respect to the cylinder whereas the load isconnected to the second piston. Fluid is controllably exhausted from thevariable volume chamber between the pistons after the first piston hasbeen stopped and while the second piston connected to the load is stillbeing driven by linid pressure. The variable volume chamber between thepistons becomes a cushioning chamber and is effective at any of thepredetermined positions at which the first piston may be stoppedrelative to the cylinder so that the cushioning operation is the same atall positions.

The present invention also relates to the employment of a series ofpistons and cylinders in which each cylinder except one end cylinder ofsuch series is connected to the piston of an adjacent cylinder to bemoved thereby. One of the elements of the series, such as a cylinder isconnected to a xed element, and a load element is connected to each pairof intermediate movable elements consisting of a piston and a connectedcylinder. A load element is also connected to any end element of theseries which is movable with respect to the xed element. A stopmechanism is positioned between each cylinder `and its associated pistonfor selectively stopping such piston relative to its cylinder in any oneof a plurality of predetermined positions, which stop mechanismpreferably includes a second piston in such cylinder as discussed aboveto provide for cushioning the stopping `of the lirst cylinder and loadconnected thereto. A control means is provided for each cylinder and itsassociated piston so that adjacent load elements may be moved relativeto each other, any load elements more remote from the fixed elementbeing also moved. The structure just described has a variety of uses,one use being the moving of the sliding saws of a sawmill edger toselected positions relative to each other.

The present invention also relates to a simplified control system whichcan be employed either with the power operated device of said copendingapplication or with the power operated device of the present invention,including the series arrangement yof the pistons and cylinders referredto above. In the case of the series arrangement of pistons andcylinders, the control system may include mechanism by which extensionof the series beyond the space limits of the machine in which it isincorporated is prevented and by which a deiinite arrangement of theload elements results when the operator actuates the control mechanismin a manner which would cause the series of pistons and cylindersreferred to to attempt to expand beyond the space limits of the machinein the absence of the control referred to.

It is therefore an object of the present invention to provide animproved power operated device including a piston and cylinder in whichthe piston is stopped by a stop mechanism in -any `one of a plurality ofpredetermined positions and the stopping of such piston is cushioned atany one of such positions by an auxiliary variable volume chamber Withinthe cylinder.

Another object of the invention is to provide a simplilied control for apower operated device in which a piston is stopped in one direction ofits movement relative to its cylinder in any one of a plurality ofpredetermined positions by a one direction stop device and in which thepiston is controlled so that its initial movement is always in adirection away from such stop device and its iinal movement is in adirection toward such a stop device.

Another object of the invention is to provide a power operated device inwhich a plurality of pistons and cylinders are connected in series andin which a stop device is employed between each cylinder and itsassociated piston to enable a plurality of load devices connected tosaid pistons and cylinders to be brought to selected predeterminedpositions relative to each yother and to a lixed element.

A further object of the invention is to provide a power operated deviceemploying a plurality of cylinders and pistons connected together inseries for moving a plurality of load elements to selected predeterminedpositions relative to each other and to a xed element in which a stopmechanism is employed between each piston and its cylinder to stop saidpiston in a predetermined position relative to its cylinder and thestopping of each piston relative to its cylinder is cushioned bycontrollably exhausting duid from an auxiliary variable volume chamberwithin such cylinder. Y

Other objects and advantages of the invention will appear in thefollowing description of preferred embodiments thereof shown in theattached drawing of which: A Fig. l is a diagrammatic view `of a poweroperated device in accordance with the present invention with acushioning cylinderV shown in vertical section;

Fig. 2 is a diagrammatic vertical section longitudinally through alumber edger showing a possible arrangement of three of the cylinders ofthe present invention for moving edger saws to preselected positions;

Fig. 3 is a diagrammatic front view on a smaller scale of the cylinderarrangement of Fig. 2 with the various elements spread vertically andwith the control elements omitted.

Fig. 4 is a view similar to Fig. 3 on a larger scale showing the racksof the stop mechanism in approximately their relative operatingpositions and certain of the control elements but -with the cylindersomitted; and

Fig. 5 is a top view of a push button control box for the cylinders ofFigs. 2 and 3.

Referring more particularly to the drawings, the power operated deviceof the present invention includes a cylinder in which are reciprocablymounted a rst piston 12 secured to one end of tubular connecting element14 extending through a packing gland 16 in one end 18 of the cylinder.The tubular connecting element 14 has secured .thereto exteriorally ofthe cylinder 10 a load connecting'member 20 which may be connected to aload to move such load as described below. A second piston 22 is alsopositioned in the cylinder 10 so as to be on the other side of thepiston 12 from the end 18 of the cylinder. The piston 22 is secured to apiston rod 24 which extends through the interior `of the tubularconnecting element 14 and through a packing gland 26.at the end of thetubular connecting element 14`remote from the piston 12. The cylinderand piston 12 provides `a rst variable volume chamber 28 between thepiston 12 and the end 18 of the cylinder; a second variable volumechamber 30 between the pistons 12 and 22 and a third variable volumechamber 32 between the piston 22 and the closed end 34 of the cylinder.The piston rod 24 is securedat its end remote from the piston 22 to alaterally extending rack connecting member 36 having its other endconnected to a rack member 38 mounted for reciprocation on a guide 39.It will be apparent that the two pistons 12 and 22 may move together inthe cylinder 10 to move the load connecting member 20 and lrack member38 and also that the piston 12 can have limited movement relative to thepiston 22 so that the load connecting member 20 may have limitedmovement with respect to the rack 38.V

' The rack 38 hasY a plurality of notches therein providing abutments 40for engagement with a pawl 42 which is pivoted to a bearing member 46which is stationarily mounted with respect to the cylinder 10, thedotted line 47 indicating that the bearing member 46 Yand cylinder 10are secured together mechanically. The

pawl 42 is urged toward engagement with the rack 38 by a tension spring48 extending between one arm of the Y pawl and the bearing member 46.The pawl can be retracted from engagement with the rack 38 by either oneof'two solenoids 50 and 52, the plungers of the solenoids beingconnected together and to the pawl 42 through a tension spring 54. Y `Itwill be appreciated that suitable guides (not shown) may be provided forthe solenoid plungers to maintain them in alignment with their re- Yspectivesolenoids. v

Fluid under pressure from a pump 56 may be selectively delivered intoeither of the'variable volume chambers 28 and 32 under control of asolenoid operated valve 58 through conduits 60 and 62, respectively, andalso exhausted from such chambers through such conduits. The poweroperated device of the present invention is particularly adapted foroperation with compressed air in which case the pump 56 may be an aircompressor, although the device may be operated by other gases underpressure or by a hydraulic uid under pressure. In the position of thevalves 58 shown in Fig. l, fluid from the pump 56 is being deliveredthrough the conduit 68 into the chamber 28 and is being exhausted fromthe chamber 32 through the conduit 62 and a discharge conduit 64. In theposition of the device shown in Fig. l, `the piston 12 is being drivento the left by uid under pressure and the pawl 42 has just engaged anabutment 40 on the rack 38. Under these conditions, uid is beingexhausted from the chamber 30 between the pistons 12 and 22 through anannular space 66 within the tubular connecting element 14 and betweenthe walls of such element and the piston rod 24 and then through aconduit 68 and a control valve 70 operated by a link 72 connected to thepawl 42 and through an adjustable metering valve 74. Although the piston22 by reason of its mechanical connection to the rack 38 has beenstopped by the pawl 42 in a selected predetermined position, the piston12 connected to the load element 20 continues to move by reason of theuid pressure admitted to the chamber 28 but such movement is cushionedby the discharge of fluid from .the chamber 30 under control of themetering valve 74.

1t will be noted that any time the pawl 42 is withdrawn from engagementwith the rack 38, the valve 70 is actu ated to connect the conduit 68and therefor the chamber 30 with the high pressure lside of the pump 56through.- a conduit '76. Under these conditions fluid under pres-V sureis supplied to the chamber 30 through the conduit 76, valve 70, conduit68 and annular space 66. ThisA means that the pistons 12 and 22 areseparated from each other each time the pawl `42 is retracted rom'therack 38. This conditions the piston for the cushioning action just`described when the pawl is again employed to stop movement of the rackto the left in Fig. l. Y

The valve 58 is actuated by a solenoid 80, the valve being moved fromthe position shown in Fig. yl to a position connecting the pump 56 withthe conduit 62 and connecting the conduit 60 with the discharge conduit64 whenever the solenoid `is energized and being returned to theposition shown in Fig. l when the solenoid 8G is deenergized. Thesolenoids 50, 52 and 80 are controlled by a plurality of push buttons82, in conjunction with contact strips 84 and 86 secured to the rack 38and insulated therefrom and also in conjunction with a switch 88actuated by pivotal movement of the pawl 42 and a limit switch 90adjacent one end of the rack 38. Each of the push buttons 82 has acontact element 92 stationarily mounted with respect to the cylinder 10and slidably engaging one or the other of the contact strips 84 or 86Ydepending upon the position of the rack relative to the cylinder 10, orengaging an insulating member 164) positioned in a gap between thecontact strips 84 and 86.' VA contact element 102 is positioned tocontactrthe contact strip 84 in any position of such strip and similarlya contact element 104 is positioned to engage the contact strip 86 inany of its positions. The push buttons 82 are part of an assembly of thebutton locking type in which any button remains depressed when depressedand in which the depression of one button releases any other buttonpreviously depressed. Such push button assemblies are conventional andwill not be further described.

In Fig. 1, the push button 82.has been depressed but, in the position ofthe rack shown, any circuit through such'push button has been broken byreason ofthe fact that its associated contact element 92 is inengagement with the insulating member 100. The solenoids 50, 52

and 80 are all deenergzed so that the valves 7.0 and 58 are in theposition shown in Fig. l and the piston 12 will continue to move to theleft in Fig. 1 until it engages the piston 22 at which time any loadconnected to the load connecting element 20 will have reached apredetermined position set by the position of the pawl 42 engaging theabutment 40 on the rack 38 corresponding to the push button 82'.

One contact of each of lthe push buttons 82 is connected to the one sideof the line L1 through a conductor 106 and such conductor continues toone of the normally open contacts of the limit switch 90. Each of theother contacts of the push buttons 82 is connected to a correspondingcontact element 92 making sliding contact with a contact strip 84 or 86.The contact element 102 engaging the contact strip 84 is connected by aconductor 198 to one side of the solenoid 50, such conductor 108 alsocontinuing to the other normally open contact of the limit switch 90.The conductor 108 is also connected to a conductor 110 through theswitch 88 actuated by the pawl 42 and such conductor 110 is connected toone side of both the solenoid 52 and the solenoid 80, the switch 88being closed when the pawl 42 engages the rack 38. The conductor 110 isalso connected to one of the normally closed contacts of the limitswitch 90, the other normally closed contact thereof being connected tothe contact element 104 in engagement with the contact strip 86 througha conductor 112. The other sides of the solenoids 50, 52 and 8i) areconnected to the other side of the line L2 through conductors 114 and116, respectively. In the normal position of the limit switch 90 shown,the conductors 110 and 112 are connected together by a switch element118. If the rack 38 is moved toward the right in Fig. l, a switchoperating element 120 engages the switch element 118 to break thecircuit between conductors 110 and 112 and further movement of the rackto the right cause the switch element 118 to complete a circuit betweenconductors 106 and 108.

If a push button such as button 82x to the left of push button 82 ofFig. 1 is depressed, push button 82' is released from its lockedposition to open the circuit through such push button and a circuit isclosed through the last depressed push button. This closes the circuitfrom the line L1 through the push button 82x, contact strip 84,

conductor 108 and the solenoid 50 to line L2. This energizes solenoid 50but solenoid 50 is unable to retract the pawl 42 from the rack 38 untilthe rack has been moved to the right to move the abutment 40 away fromthe pawl 42. Since the conductor 108 is connected to conductor 110through the switch 88, a circuit is also completed from conductor 108through conductor 110 and through the solenoid 80 to the line L2. Theresulting energization of the solenoid 80 operates switch 58 to connectconduit 62 with the pump 56 to introduce fiuid under pressure into thechamber 32 at the left end of cylinder and also connects conduit 60 withdischarge conduit 64 to exhaust fluid from chamber 28. The piston 22moves to the right in Fig. 1 to move the rack 38 to the right to releasethe pawl 42 from the rack. Pivoting of the pawl 42 breaks the circuitthrough the switch 88 to deenergize solenoid 80 and allow the valve 58to return to the position shown in Fig. l. The circuit through thesolenoid 50 still remains Vcompleted. to hold the pawl out of contactwith the rack 38 and the position of valve 58 just described introducesfluid under pressure through the conduit 60 into the chamber 28 of thecylinder 10 while exhausting uid from the chamber 32 through the conduit62. The valve 70 was actuated by the pawl 42 when such pawl was releasedfrom the rack 38 to a position connecting conduit 68 With conduit 76 sothat uid pressure from the pump 56 was delivered into the chamber 30between the pistons 12 and 22. This caused the two pistons 12 and 22 toseparate and the actuation of valve 58 by the solenoid 80 causes the twoseparated pistons to move to the left in Fig. 1.

When the rack approaches the desired position corresponding to pushbutton 82x, the sliding contact element 92x associated with push button82x engages the insulating member 1,00 so that the circuit throughsolenoid 50 is broken. The pawl 42 is pivoted by the spring 48 intoposition to engage the abutment 46x corresponding to push button 82x andat the same time valve 70 returns to the position shown in Fig. l sothat the chamber 30 is connected to exhaust through the metering valve74. When the rack abutment 40x strikes the pawl 42, the piston 22connected thereto is stopped but piston 12 continues to move to the leftcarrying the load connecting element 20 therewith and such movement iscushioned by throttling of iluid through the valve 74 until the piston12 engages the piston 22. The load is thus stopped in a predeterminedposition corresponding to the push button 82x and the stopping of theload is cushioned by the controlled iinal movement of piston 12.

lf a push button, such as push button 82y to the right of the previouslydepressed push button 82' is depressed, push button 82 is released tobreak any circuit therethrough and a circuit is completed through thepush button 8251. This circuit may be traced from the line L1 throughconductor 106, push button 82)', contact element 92) corresponding topush button 82y, contact strip 86, contact element 104, conductor 112,the normally closed contacts of switch 90, conductor 110, conductor 114,and solenoid 52 to the other side of the line L2. This energizessolenoid 52 to condition it to retract pawl `42 from the rack 38 butsuch pawl will not be retracted until the rack 38 has moved to theright. The circuit just traced also energizes solenoid 80, since thecircuit is also completed from the conductor 110 through the solenoid tothe other side of the line L2. The energization of solenoid 80 actuatesthe valve 58 to supply fluid under pressure through conduit 62 to thechamber 32 at the left of the cylinder 10 and exhaust fluid from thechamber 28. As soon as the rack moves toward the right, the pawl 42 isretracted. The rack 38 continues to move to the right until theinsulating member moves under the contact element 92)) to break thecircuit through such contact element. This occurs after the abutment 40ycorresponding to the push button 82y has progressed a short distance tothe right of the pawl 42 of Fig. l. When the circuit referred to isbroken, both the solenoid 52 and the solenoid 80 are deenergized so thatthe pawl is positioned to engage the abutment 40) and at the same timethe valve 58 is returned to its position shown in Fig. l so as to againmove the pistons '12 and 22 toward the left in such ligure. At the timethe pawl was retracted from the rack 38 and during the movement of therack 38' to the right just described, the valve 70 was actuated tosupply luid under pressure to the chamber 30 between the pistons 12 and22 so that such pistons are separated and as soon as the pawl returns tothe position shown in Fig. l, the chamber 36 is connected to beexhausted through the metering valve 74 to cushion the final movement ofpiston 12 toward piston 2,2.

The limit switch 9i) is not, in general, needed with a system having asingle cylinder 10 but is preferably employed with a system havingseveral cylinders and pistons connected in series, as described below.Such a limit switch is of primary importance where the combined travelof the pistons of several cylinders connected in series is greater thanthe space available in a given machine. Its operation will be explainedbelow. The switch 90 can be eliminated from a single cylinder system byconnecting the conductors and 112 together.

A possible arrangement of a series of three cylinders 10, 10a and 10b isshown diagrammatically in Fig. 3. In such ligure, the piston rods 24,24a and 24h of the respective cylinders are shown connected to racks 38,381i and 38b through the rack connecting members 36, 36a and 36h,respectively, the racks sliding on guides 39.

"7 The rload connecting member 20 associated with the piston 10 isconnected to the hub of an edger saw 124 sliding on an'arbor 126journaled in a frame 128, the guides 39 for the racks 38 being supportedin such frame. The load connecting member a associated with Vthecylinder 10a is connected to the hub of a second edger saw 124x: slidingon the arbor 126 and also to the cylinder 10 so as to move the cylinder10 with the tubular member 14a of the cylinder 10a. Similarly the loadconnecting member 20b connected to the tubular connecting element 14associated with Vthe cylinder 10b is connected to the cylinder 10a tomove such cylinder and also to the hub of a third edger saw 124b slidingon the arbor 126. It will be apparent from Fig. 3 that movement of thetubular connecting element 14 relative to its cylinder 10 will move theedger saw 124 relative to the other edger saws. Also, movement of theconnecting element 14a relative to cylinder 10a will move both edgersaws 124 and 12411 relative to edger saw 124b and movement of thetubular connecting element 14b relative to cylinder 10b will move allthree edger saws 124, 124a and 124b relative to the frame 128 of theedger. It will be further appreciated that the racks 38, 38a and 38bwill move on their respective guides concurrently with the tubularconnecting members-14, 14a and 14b, respectively, except for thecushioning movements of the tubular connecting elements with respect tothe racks as described with reference to Fig. l.

The racks 38, 38a and 38b in Fig. 3 have been shown as being spacedvertically from each other in order to provide room to show thecylinders 10, 10a and 10b, but in Fig. 4 the cylinders have beenomitted, since they would be largely behind the racks, and the racks areshown in approximately the relative positions they would assume in anactual machine. In Fig. 4, the pawls 42, 42a and 42b with theirassociated operating solenoids 50 and 52 are shown along with theirassociated pawl operated control valves 70 and control switches 8S. Theother elements of the control mechanism is also omitted from Fig. 4.

A possible arrangement of the various cylinders 10, 10a and 10b withassociated racks 38, 38a and 38b is shown in diagrammatic verticalsection in Fig. 2, also showing one of the edger saws 124, the usualdrive Vrolls and hold down rolls for the lumber passing through suchYedger being omitted. The racks are shown as being mounted upon the guide39 and as being connected to the piston rods 24, 24a and 24b,respectively, through the rack connecting members 36, 36a and 36b,respectively. Also the load connecting element 20 associated with piston10 is connected to the hub of the saw 124 whereas the load connectingelement 20a associated with the cylinder 10a is also connected to thecylinder 10 as well as to one of the saws and the load connectingelement 20b associated with the cylinder 10b is connected to thecylinder 10a as well as to one of the saws. The relative positions ofthe pawls 42, 42a and 42b with respect to their racks X38, 38a and 38bis also indicated in Fig. 2, as is also the relative positions o"Y thecontact strips 86 and contacts 104 for the respective racks. In Fig. l,a row of push buttons 82 is shown associated with the control system forthe cylinder 10 and, as indicated in Fig. 5, a control panel 130 maycontain such row of push buttons 82 and also a row of push buttons 82afor the cylinder 10a and a row of push buttons 8217 for Ithe Vcylinder10b.y

Each of the push buttons 82 may correspond to a definite distancebetween the saws 124 and 124a, for example, the push button at the leftof the row of push buttons 82 may correspond to distance of two inchesbetween saws, the next push button to the right corresponding to adistance o four inches between the saws and so on, the distancecorresponding to each push button progressively toward the rightincreasing by an increment of two inches. Such increment corresponds tothe distance between twosuccessiveabutments-40 on a 8 rack 38. Thus,pushing any one of the push buttons 82 will automatically cause the saws124 and 124a to assume the distance apart which correspondsV to the pushbutton 82 which is depressed. `In a similar manner, the push buttons 82a`set the distance between the saws 124:1 and 1'24b and the push buttons821? set the distance of the saw 124b from a xed point on the frame 128.Thus in most cases' the edger Voperator can make a desired change in thepositions of the edger saws for a particular Y board by pushing one pushVbutton and in any case, not more than one push button for each saw tobe moved. It will be apparent that a greater or lesser number of sawswith associated pistons can be employed and that the particular controlsystem illustrated can be employed in other environments where it isdesired to bring one or more load elements to a precise predeterminedposition relative to another load element or to a xed element.

It will be further apparent that any attempt to spread all of the edgersaws of Fig. 4 their maximum distance apart would, in general, exceedthe maximum space available in an edger. If it be assumed that the sawsin Fig. 4 are spread so as to occupy all of the space available in theedger, the control system of the present invention is such that the saws124a and 124b, either individually or together, can be moved further tothe right in Fig. 4 by depressing a correctly selected single pushbutton even though the saw 124 cannot be moved further to the right.That is to say,V if a push button at the right end of the row of pushbuttons 82 in Fig. 5 were depressed, the cylinder 10 (Fig. 3) wouldattempt to move the saw 124 further to the right in Fig. 4 and thiswould cause engagement of the switch element 11S of IFig. l by theswitch operating element 120, thus opening the circuit betweenconductors 110 and 112. The elect is the same as if the circuit througha push button were broken during motion of the rack 38 to the right bythe insulating member moving under the corresponding contact element 92.The mechanism proceeds through the stopping cycle above described inwhich the motion of the rack is reversed and the pawl is engagedagainstrone Vofthe abutments 40`of the rack 38. The switch 90 is suchthat the circuit between the conductors 110, 112 remains broken untilsubsequent motion of the rack to the left is eected by depressing a pushbutton to the left of a previously depressed push button in one of therows of control push buttons.

Depressingany of the push buttons 82a or 82b at the right of Fig. 5would cause movement of the saws l24a or 124b, or both to the right andthis would also cause movement of the rack 38 to the right of Fig. 4 orFig. l. 'If the motion of the rack 38 continues to the right in Fig. l,past the position merely opening the circuit between the conductors andV112, the switch element 118 completes a circ-uit between the conductors106 and 108. The effect is the same as depressing a push button I82associated with the cylinder 10 to the left of the previously depressedpush button and the rack is moved to the left in Fig. 1 in the samemanner as described above until the switch member 118 is released toopen the circuit between the conductors 106 and 10S. This causesstopping 'of the rack relative to the cylinder as described above. 'Ifthe range of movement of the saws 124a and 124b is sulicient to exceed'the'distance available for movement of the saws in the edger when thesaw 124 is immediately adjacent the sawY 124a, a limit switch 90 may beincludedV in the control circuit for the saw 124a and cylinder 10a. Y

The general operation of the control system of Fig. 1 is asfollows'.'I'he'apparatusl will'normally be at rest with one of the push buttons,such as push button 82 depressed, and the two pistons 12 and 22 Vwillunder such conditions be in contact Vwith-each other such'that VthepositionV of the load connecting element 20Ybears a detinite'relatontothe position of the rack 38 as established by the pawl 42. The pawl 42and cylinder 1li are either xed to the frame of the machine or connectedso as to move together. Upon depressing a push button, such as pushbutton 82V, to the right of the previously depressed push button 82',such previously depressed push button is released and also valve 58 isactuated by the solenoid 843 to supply `lluid under pressure into thechamber 32 to drive the pistons to the right, uid being exhausted from achamber 2S through the valve 58. As soon as the rack 38 starts to moveto the right, the pawl 42 is withdrawn from engagement with the rack bythe solenoid 52 to actuate the valve 70 which supplies fluid pressure tothe chamber 30 between the pistons 12 and 22 to separate the pistons.When the circuit through the push button 82v is broken by the insulatingmember lill) moving under the contact element 92y, the pawl 42 returnsto the position shown in Fig. l to cause the valve 79 to connect thechamber 3i) vfor regulated discharge through the valve 74.Simultaneously, the valve 58 is returned to its position shown in Fig. lso as to supply fluid pressure to the chamber 28 and exhaust fluid fromthe chamber 32. This causes the rack 38 to return until it engages thepawl 42. After the rack 38 is stopped, the piston 12 continues to movewhile being cushioned by iluid in the chamber 30 until the piston 12contacts the piston 22 at which time the -load element 20 is stopped ina delinite position with respect to the rack 38.

When a push button, such as push button 32x, to the left of thepreviously depressed push button 82 is depressed, push button 82 isreleased and the circuit completed through the push button 82x causesenergization of solenoids 50 and 8l), the solenoid 8i) actuating valve58 to supply fluid under pressure to the chamber 32 and exhaust fluidfrom the chamber 28. rIhis starts movement of the rack 38 tothe right inFig. l so that the pawl 42 can be withdrawn by the solenoid 59, suchwithdrawal of the pawl also actuating valve 70 to supply uid underpressure to the chamber 3l) between the pistons 12 and 22. Alsoactuation of the pawl 42 breaks the circuit through the solenoid 80 atthe switch V88 so that Huid under pressure is then supplied by the valve58 to the chamber 28 and exhausted from the chamber 32 to drive thepistons 12 and 22 to the left. VAs soon as the insulating member 109cornes under the contact 92x, the circuit to solenoid 50 is broken tocause the spring 48 to again position the pawl 42 in the path of anabutment 40 to stop the rack 38 and piston 22. Return movement of thepawl 42 to the position shown in Fig. l actuates the valve 70 to exhaustfluid from the chamber 30 between the pistons 12 and 22 through themetering valve 74 to cushion the stopping movement of the loadconnecting element 20 and load connected thereto,

When a plurality of cylinders, such as cylinder 10, a and 10b of Fig. 3are connected in series with the pistons of one cylinder moving the nextcylinder, the distances between load elements, such as the saws 124,12451 and 124k, may be independently set. In the system shown, anymovement of saw 124b with respect to a stationary element causesmovement of saws 124a and 124 concurrently therewith and any movement ofsaw 124a with respect to saw 12419 also causes movement of saw 124. Themovement of saw 124 relative to saw 124a is under control of the seriesof push buttons 82 of Fig. 5, whereas the movement of saw 124a relativeto saw 124b is under control of the series of push buttons 82a andmovement of the saw 124b relative to the frame of the machine is undercontrol of the series of push buttons 82]). The limit switch 9i? of Fig,l stops the movement of saw 124 if the total extension of the varioussaws relative to a stationary element exceeds the space available forsuch extension, and also allows continued movement of saw 124a or 124aand 124b toward the saw 124 after such saw has been stopped. Upon returnmovement of saw 124a to the left in Fig. 4, the saw 124 remains at itsextreme right position until the distance between saws 124 and 124acorresponds to the distance set by push buttons 82 after which itfollows saw 124a at such distance.

While I have disclosed the preferred embodiments of my invention, it isto be understood that the details thereof may be varied and that thescope of the invention is to be determined by the following claims.

I claim:

l. A fluid operated power device for moving a load element selectivelyto any one of a plurality of predetermined positions comprising acylinder, a rst piston positioned in and movable longitudinally of saidcylinder to provide a rst variable volume chamber at one end of saidcylinder, a second piston positioned in and movable longitudinally ofsaid cylinder, said pistons having limited movement relative to eachother longitudinally of said cylinder to provide a second variablevolume chamber between said pistons, means for supplying a uid underpressure to said first and second chambers to cause said pistons toseparate and to move together in one direction, a movable load elementmoved by said rst piston, a stop mechanism for selectively stopping saidsecond piston in any one of a plurality of predetermined positions, andmeans to controllably exhaust fluid from said second chamber to providefor cushioned further movement of said first piston by said fluid underpressure in said first chamber until said rst piston and said loadelement reaches a predetermined position relative to said second piston.

2. A lluid operated power device for moving a load element selectivelyto any one of a plurality of predetermined positions comprising acylinder, a first piston positioned in and movable longitudinally ofsaid cylinder to provide a rst variable volume chamber at one end ofsaid cylinder, a second piston positioned in and movable longitudinallyof said cylinder, said pistons having limited movement relative to eachother longitudinally of said cylinder to provide a second variablevolume chamber between said pistons, means for supplying a fluid underpressure to said first and second chambers to cause said pistons toseparate and to move together in one direction, a movable load elementmoved by said rst piston, a stop mechanism for selectively stopping saidsecond piston in any one of a plurality of predetermined positions, andmeans to controllably exhaust lluid from said second chamber to providefor cushioned further movement of said lirst piston by said lluid underpressure in said first chamber until said rst piston and said loadelement reaches a predetermined position relative to said second piston,said second piston providing a third variable volume chamber at theother end of said cylinder, mid means for alternately supplying a fluidunder pressure to said third chamber tomove said pistons in the otherdirection.

3. A Huid operated power device for moving a load element selectively toany one of a plurality of predetermined positions comprising a cylinder,a rst piston positioned in and movable longitudinally of said cylinderto provide a lirst variable volume chamber at one end of said cylinder,a second piston positioned in and movable longitudinally of saidcylinder, said pistons having limited movement relative to each otherlongitudinally of said cylinder to provide a second variable volumechamber between said pistons, means for supplying a lluid under pressureto said first and second chambers to cause said pistons to separate andto move together in one direction, a movable load element moved by saidiirst piston, a stop mechanism for selectively stopping said secondpiston and load element in any one of a plurality of predeterminedpositions, and means to controllably exhaust fluid from said secondchamber to provide for cushioned further movement of said rst piston bysaid fluid under pressure in said first chamber until said iirst pistonand said load element reaches a predetermined position relative to saidsecond piston, said second piston providing a third variable volumechamber at the other end of said cylinder, means for alternatelysupplying a Huid under pressure to said third chamber to move saidpistons in the other direction, control means for causing said pistonsto selectively move` said load element to any one of said positions ineither direction,

said control means including means toV cause the .final movement of saidpistons to any of said positionstto be in said onel direction againstsaid stop mechanism and to cause the initial movement of said pistonsfrom any of vsaid positions to be in the reverse of said one direction.

' 4. A fluid operated power device for moving a load 'elementselectively to any one of a plurality of predetermined positions, saiddevice comprising a cylinder, a first piston positioned in and movablelongitudinally of said cylinder to provide a irst variable volumechamber at one end of said cylinder, a second piston posil tioned andmovable longitudinally of said cylinder, said lpistons having limitedmovement relative to each other Ylongitudinally of said cylinder toprovide a second variable volume chamber between said pistons, controlmeans for supplyingV a fluid under pressure to said first and secondchambers to cause said pistons to separate and to move together in onedirection, a movable load Velement moved by said iirst piston, a stopmechanism for selectively stopping said second piston from movement Y insaidl one direction in any one of a plurality of predeterminedpositions, said control means including means Ysure to said thirdchamber to move said piston in the other direction, said control meansalso including means causing the initial movement of said pistonsrelative to said cylinder from any one of said positions to be in'adirection opposite said one direction and for causing the rnalmovementof said pistons relativeVto said piston to any one of said.positions to be in said one direction, said control means alsoincludingmeans for selectively. releasing and engaging said stop mechanism toprovide for controlled movementof said piston member relativerto saidcylinder in said one direction.

5. Atfluid/operated power device for moving a load element selectivelyto any one of a plurality of predetermined positions, said devicecomprising a plurality of cylinders, a first piston positioned in eachof said cylinders andV movable longitudinally thereof to provide a firstvariable volumechamber at one end of each of said cylinder, a. secondpiston positionedtand movable longitudinallyof each of said cylinders,said pistons in each cylinder having limited movement relative to eachother longitudinally of said cylinders to provide a second variablevolume chamber between said pistons in each cylinder, control meansrforselectively supplying a iiuid under pressure to said lirst and secondchambers of each cylinder to cause said pistons in each cylinder toseparate andrto move togetheriin one direction, said cylinders and iirstpistons being connected in series, adjacent cylinders except therendAcylinder of said series being connected to the rst piston of an adjacentcylinder in said series, a movable load element moved by said ,t rstpiston of each cylinder, a stop mechanism Vfor selectively stopping saidsecond piston of each cylinder in any one of a plurality ofpredeterminedppositions relative to its cylinder, said control meansincluding means to controllably exhaust fluid from said second chamberof `each cylinder to provide for cushioning further movevment of eachiirst piston relative to its cylinder and second piston therein, saidsecond Apiston in each cylinder providing a third variable volumechamber at the other end thereof, said control means including means forsupplying a fluid under pressure to said third chamber of each cylinderto move its pistons in the other direction, said controltmeans alsoincluding means causing the initial movementof each of said secondpistons relative to its cylinder to be in a direction opposite said onedirection and for causing final movement of each of said second pistonsrelative to its cylinder to be in said one direction, said control meansalso including means for selectively releasing and engaging said stopmechanisms to provide for controlled movement of said second pistonmembers relative to their cylinder in said one direction.

6. A fluid operated device for moving a plurality of load elementsselectively to predetermined positions relative to each other and to afixed element, which device comprises a plurality of cylinder members,first and second piston members positioned in each of said cylindermembers and movable longitudinally thereof, said piston members in eachcylinder having limited longitudinal movement with respect to each otherto provide a variable volume chamber therebetween, said cylinder membersand first piston members being connected in a series in which eachcylinder member except the end cylinder member of said series isconnected to be moved with the iirst piston member of an adjacentcylinder member, one of said members being connected to a fixed member,said iirst piston members being connected to load elements to move saidload elements, a `stop mechanism between each cylinder member and itssecond piston member for selectively stopping its said second pistonmember against movement in one direction in any one of saidpredetermined positions relativeV to its cylinder member, control meansfor each of said cylinder members for selectively introducing uidundertpressure into the ends of each of said cylinder members to movesaid piston members relative to their cylinder members in eitherdirection to said predetermined positions, said control means includingmeans causing the initial movement of each second piston member relativeto its cylinder member from any one of said positions to be in adirection opposite said one direction and Yfor causing the inal movementof each said second piston member relative to its cylinder member to anyone of said positions to be in said one direction, Said control meansalso including means for selectively engaging said stop means for eachsaid second piston member to provide for controlled movement of eachsaid second piston member relative to its cylinder member in said onedirection and including means for supplying uid under pressure into saidvariable volume chamber between the piston members in each of saidcylinder members to separate said piston members during movement thereofrelative to their cylinder members and to controllably exhaust uid fromeach said chamber during said iinaltmovement of the associated rstpiston in said one direction.

7. A iiuid operated device for moving a plurality of load elementsselectively to predetermined positions relative to each other and to aiixed element, which device comprisessa plurality of cylinder members, apiston member positioned in each of said ,cylinder members and movablelongitudinally thereof, said cylinder and piston members being connectedin a series in whicheach cylinder member except the` end cylinder memberofV said series is connected to be moved with the piston member of anadjacent cylinder member, one of said members being connected to a fixedmember and the other of said members being connected to load elements tomove said load elements, a stop mechanism between each cylinder memberand its piston member for selectively stopping a piston member againstmovement inVone direction in any one of a plurality of predeterminedpositions relative to its cylinder member and control means for each-ofsaid cylinder members and its piston member for selectively introducingVuid under pressure into the ends of said cylinder members to move saidpiston members relative to their cylinder members in either direction tosaid predetermined positions, said control means including means causingthe initial movement of each piston member relative to its cylindermember from any of said positions to be in a direction opposite said onedirection and for causing the iinal movement of said piston relative toits cylinder to any of said positions to be in said one direction, saidcontrol means also including means for selectively releasing andengaging said stop means to provide for controlled -movement of eachpiston member relative to its cylinder member to said positions.

8. A fluid operated device for moving a plurality of load elementsselectively to predetermined positions relative to each other and to afixed element, which device comprises a plurality of cylinder members, apiston member positioned in each of said cylinder members and movablelongitudinally thereof, said cylinder and piston members being connectedin a series in which each cylinder member except the end cylinder memberof said series is connected to be moved with the piston member of anadjacent cylinder member, one of said members being connected to a xedmember and the others of said members being connected to load elementsto move said load elements, control means for each cylinder member forselectively stopping its piston memberin any one of a plurality ofpredetermined positions including end and intermediate positionsrelative to its cylinder member and means for each of said cylindermembers for introducing fluid under pressure into the ends of each ofsaid cylinder members to move each of said piston members relative toits cylinder member in either direction to said predetermined positions.

9. A fluid operated device for moving a plurality of load elementsselectively to predetermined positions relative to each other and to axed element, which device comprises a plurality of cylinder members, apiston member positioned in each of said cylinder members and movablelongitudinally thereof, said cylinder and piston members being connectedin a series in which each cylinder member except the end cylinder memberof said series is connected to be moved with the piston member of anadjacent cylinder member, one of said members being connected to a fixedmember and the others of said members being connected to load elementsto move said load elements, means for introducing iiuid under pressureinto the ends of each of said cylinder members to cause movement of eachsaid piston member relative to its cylinder member in either direction,and control means for selectively stopping each of said piston membersin any one of a plurality of predetermined positions including end andintermediate positions relative to its cylinder member.

l0. A tiuid operated device for moving a plurality of load elementsselectively to predetermined positions relative to each other and to aiixed element, which device comprises a plurality of cylinder members, apiston member positioned in each of said cylinder members and movablelongitudinally thereof, said cylinder and piston members being connectedin a series in which each cylinder member except the end cylinder memberof said series is connected to be moved with the piston member of anadjacent cylinder member, one of said members being connected to a xedmember and the others of said members being connected to load elementsto move said load elements, control means for each cylinder member forselectively stopping its piston member in any one of a plurality ofpredetermined positions including end and intermediate positionsrelative to its cylinder member, means for each of said cylinder membersfor introducing fluid under pressure into the ends of each of saidcylinder members to move each of said piston members relative to itscylinder member in either direction to said predetermined positions, andmeans controlling the 14 introduction of said fluid into the endcylinder of said series spaced from said iixed member for stopping themovement of the end member of said series spaced from said lixed memberwhen said end member reaches the end of the space available for movementof said Vend member away from said fixed member while enabling continuedmovement of intermediate members of said series relative to said iixedmember and said end member.

11. A power operated device for moving load elements of a longitudinallyextending series of elements selectively to predetermined positionsrelative to each -other and to a iixed element positioned at one end ofsaid series, said load elements being movable within a space extendinglongitudinally of said series and said device comprising power means formoving each of said load elements within and longitudinally of saidspace, and control means for said power means including selecting meansfor causing operation of said power means to move any selected loadelement to any selected position of a plurality of predeterminedpositions including extreme and intermediate positions relative to anadjacent element of said series which is on the same side of saidselected element as said one end of said series, said device alsocomprising means operated by said operation of said power means to movewith said selected load element any other load element which is on theopposite side of said selected load element from said one end of saidseries and which is at its selected predetermined position relative toit said adjacent element and movable within said space to therebymaintain said other load element at its selected predetermined positionrelative to its said adjacent element so far as permitted by said space.

l2. A power operated device for moving load elements of a longitudinallyextending series of elements selectively to predetermined positionsrelative to each other and to a xed element position at one end of saidseries, said load elements being movable within a space extendinglongitudinally of said series and said device comprising power meansincluding a cylinder and a piston for moving each of said load elementswithin and longitudinally of said space, and control means for saidpower means including selecting means for causing operation of one ofsaid pistons to move a selected load element to any selected position ofa plurality of predetermined positions including extreme andintermediate positions relative to an adjacent element of said serieswhich is on the same side of said selected element as said one end ofsaid series, said device also comprising means operated by saidoperation of said one of said pistons to move with said selected loadelement any other load element which is on the opposite side of saidselected load element from said one end of said series and which is atits selected predetermined position relative to its said adjacentelement and movable within said space lto thereby maintain said otherload element at its selected predetermined position relative to its saidadjacent element so far as permitted by said space.

13. A lumber edger comprising, an arbor, a i'ixed element at one end ofsaid arbor, a plurality of edger saws mounted on and movablelongitudinally of said arbor and forming a series of elements with saidiixed element, a power operated device for moving said saws along saidarbor selectively to predetermined positions relative to each other andto said fixed element of said series, said saw being movable within aspace extending longitudinally of said arbor and said device includingpower means for moving each of said saws within and longitudinally ofsaid space, and control means for said power means including selectingmeans for causing operation of said power means to move any selected sawto any selected position of a plurality of predetermined positionsincluding extreme and intermediate positions relative to an adjacentelement of said series which is on the same side of said selected saw assaid one end of said arbor, said device also comprising means operatedby said operation of said power means to move with said selected saw anyother saw which is on the opposite side of said selected saw from saidone end of said arbor and which isA at its selected predeterminedposition relative toits said adjacent element and movable within saidspace to thereby maintain said other saw at its selected predeterminedposition relative to its said adjacent element of said series so far aspermitted by said space.

14. A lumberpedger comprising an arbor, a iixed element at one end ofsaid arbor, a plurality of edger saws mounted on and movablelongitudinally of said arbor and forming a series of elements with saidiixed element, a power operated device for moving said saws selectivelyto predetermined positions relative to each other and to said fixedelement of said series, said saws being movable within a space extendinglongitudinally of said arbor and said device comprising power meansincluding a cylinder and a piston for moving each of said saws withinand longitudinally of said space, and control means for said power meansincluding selecting means forrcausing operation of one of said pistonsto move a selected saw to any selected position of a plurality ofpredeterminedpositionps including eXtreme and intermediate positionsrelative to anradjacent element of said series which is onV thesamevside o f said selected Vsaw as said one end of said arbor,saidrdevice also comprising means operated by said operation of said oneof said pistons to move with said selected saw any other saw whichpis onthe opposite side of said selected saw from said one end of said arborand which is at its selected predetermined position relative to its saidadjacent element and movable within said space to thereby maintain saidother saw at its selected predetermined position relative to its saidadjacent element of said series sovfar as permitted by said space.

References Cited in the tile of this patent UNITED STATES PATENTS691,692 r Von Zrweigbergk Ian. 21, 1902 UNITED STATES PATENT OFFICECERTIFICATION OF CORRECTION Patent No., 961,015 November 22, 1960 BurtonT. Randall` It is hereby certified that error appeans in the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

Column 14., line 36, for positiorf read positioned m- Signed and sealedthis 2nd day of May 1961.

SEAL) ttest:

ERNEST W0 SWIDER DAVID L` LADD Attesting Ufficer Commissioner of Patents

